The present invention relates to a new and improved construction of a controlled deflection roll, sometimes also referred to in the art as a roll with bending or sag compensation.
Generally speaking, the controlled deflection roll of the present development is of the type comprising a stationary roll support or beam and a roll shell which is mounted to be rotatable about such stationary roll support. The roll shell is supported upon the roll support or beam with the aid of at least one piston-like or punch-like pressure or support element. This pressure or support element is provided with a bearing or contact surface, upon which the roll shell, during operation of the controlled deflection roll, can slide or bear with the aid of a liquid film or layer. Additionally, the ends of the roll shell are mounted upon anti-friction bearings, typically for instance roller bearings, and these roll shell ends are sealed towards the outside by shaft seals.
Controlled deflection rolls of this type are known, for instance, from U.S. Pat. No. 4,047,273, granted Sept. 13, 1977 and U.S. Pat. No. 4,048,701, granted September 20, 1977. Although controlled deflection rolls constructed according to these principles have been found to be completely satisfactory in practise, in many instances difficulties arise in terms of providing a faultless seal of the rotatable roll shell towards the outside.
During operation, the intermediate chamber or compartment between the roll support and the roll shell receives a liquid medium, as a rule hydraulic oil, in which there must move the roller bearings or equivalent anti-friction bearing means. An excessive quantity of oil is disadvantageous in terms of realizing a faultless operation of the roller bearings. Additionally, also the shaft seals, which seal towards the outside the intermediate chamber between the roll shell and the roll support, are exposed to a large quantity of oil, so that also in this regard difficulties can arise.